Method for monitoring for a rupture in a fuel vapor container

Abstract

A method for monitoring for a rupture in a storage element of a fuel tank system having a fuel tank includes: detecting, by a mass flow sensor, thermal conductivity of an unmoved air mass in a first line of the fuel tank system; and identifying a rupture in the storage element if the detecting by the mass flow sensor detects a change in the thermal conductivity of the unmoved air mass in the first line when a second valve is in a closed state and/or when an air pump is at a standstill.

The invention claimed is: 
     
       1. A method for monitoring for a rupture in a storage element ( 5 ) of a fuel tank system, the fuel tank system having a fuel tank ( 4 ) and the storage element ( 5 ) being configured to temporarily store hydrocarbons, the fuel tank ( 4 ) and the storage element ( 5 ) being connected to one another such that hydrocarbons outgassed from fuel situated in the fuel tank ( 4 ) are stored in the storage element ( 5 ), the storage element ( 5 ) being connected to a first line ( 6 ) through which fresh air is deliverable to the storage element ( 5 ), and the storage element ( 5 ) being connected to a second line ( 12 ) connecting the storage element ( 5 ) to an intake line ( 16 ) and through which fresh air enriched with hydrocarbons is deliverable from the storage element ( 5 ) to the intake line ( 16 ), wherein a mass flow sensor ( 8 ) and an air pump ( 7 ) are arranged in the first line ( 6 ) upstream of the storage element ( 5 ) as viewed in the direction of the fresh air flow, and a second valve ( 13 ) is arranged in the second line ( 12 ) between the storage element ( 5 ) and the intake line ( 16 ), the method comprising:
 detecting, by the mass flow sensor ( 8 ), thermal conductivity of an unmoved air mass in the first line ( 6 ); and 
 identifying that a rupture has occurred in the storage element ( 5 ) if the detecting by the mass flow sensor ( 8 ) detects a change in the thermal conductivity of the unmoved air mass in the first line ( 6 ) in a case in which the second valve ( 13 ) is in a closed state and/or in a case in which the air pump ( 7 ) is at a standstill. 
 
     
     
       2. The method as claimed in  claim 1 , wherein the air pump ( 7 ) is a radial pump. 
     
     
       3. The method as claimed in  claim 1 , wherein the mass flow sensor ( 8 ) is a sensor that operates based on the calorimetric principle. 
     
     
       4. The method as claimed in  claim 3 , wherein the mass flow sensor ( 8 ) is integrated in the housing of the air pump ( 7 ). 
     
     
       5. The method as claimed in  claim 4 , wherein the fuel tank system further has a first valve arranged in the first line ( 6 ). 
     
     
       6. The method as claimed in  claim 5 , wherein a rupture in the storage element ( 5 ) is identified if the mass flow sensor ( 8 ) detects a change in the thermal conductivity of the air in the first line ( 6 ) when the first valve is in the closed state.